Fine Mapping and Identification of the Lobed-Leaf Gene in Radish (Raphanus Sativus L.)

Abstract Leaf shape is one of the important factors affecting the yield and quality of radish (Raphanus sativus L.). In this study, an F2 population obtained from the cross of the lobed-leaf cultivar J4 with the serrated-leaf cultivar WA was used for genetic analysis and gene mapping of the lobed-leaf trait. The lobed-leaf trait is controlled by a single dominant nuclear gene, and dominant over the serrated-leaf trait. Through bulked segregant analysis (BSA) and genotyping by sequencing (GBS), the lobed-leaf gene was initially mapped to the genomic region from 0.66 Mb to 8.19 Mb on chromosome R7. By using nine insertion/deletion (INDEL) markers, the gene was further narrowed down to a 1.53 Mb region. The comparative analysis of the collinear region between Raphanus sativus and Brassica napus identified Rs390250, an HD-Zip I transcription factor as the most probable candidate gene. Phylogenetic analysis supported that Rs390250 is an RCO (REDUCED COMPLEXITY) orthologous gene, and the single nucleotide variation (C425T) of Rs390250 which caused an amino acid substitution from serine (S) to lysine (L) in conserved leucine zipper domain, may destroy its DNA-binding function and be supposed to response for the morphological variation.